Process of making board from bagasse and analogous fibers



Patented Feb. 9, 1926.

JOHN K. SHAW, 0F MINNEAPOLIS, MINNESOTA.

PROCESS OF MAKING BOARD FROliI BAGASSE AND ANALOGOU$ FIBERS.

Na Drawing.

To all whom it may concern:

Be it known that I, JOHN K. SHAW, a

citizen of the United States, residing at Minneapolis, in thecounty of Hennepm and State of Minnesota, have invented certaln new and useful Improvements in Processes of Making Board from Bagasse and Analogous Fibers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a process for treating bagasse and analogous fibers and has for its object to providea method which will be more efficient in action and less costly to employ than those heretofore proposed.

lVith these and other objects in View the invention consists in the novel steps and combinations of steps constituting the process, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that the precise invention may be the more clearly understood it is said In the manufacture of wall boards used as a substitute for lumber and like material, it is very desirable indeed that the boards shall be strong and durable, that they may have a high insulating power, that they may be capable of being sawed and nailed like lumber and that they may be inexpensively produced. It has heretofore been customary to make such boards very porous,

so they will entrain large quantities of air. They are entirely distinct and difierent from paste board; they have been made of wood and other fibers, and there have been eX- perimental efiorts made inniaking substitute paste boards from well cooked bagasse and analogous fibers but in all the last named cases it has been thought'necessary to so drastically treat .the material with caustic soda or other chemicals that the strength of the fibers has been greatly injured.

In other words, these said prior processes have employed the ordinary cooking proc esses of preparing the fibers for paper making and which require the said fibers to be cooked in the chemical chosen for a time so long and to a degree so great that such fibers are suitable for paper making purposes, but

Application filed October 23, 1920. Serial No. 419,044.

are not the equivalent of those produced by this process at all, for the purpose of making boards all as will presently appear.

In addition to this, when employing bagasse fibers, the prior processes have invariably either mechanically denuded said fibers of their natural pith before treatment with the chemical solution, 01' else the caustic soda treatment has been carried out for such a length of time as to have disdevoid of their natural pith-like protuberances-so important to this invention.

According to this invention, on the other hand, the product produced is essentially a bundle of partially cooked, rough fibers capable of felting in the same sense that wool felts, and therefore is a product very different from the smooth,. drastically cooked fibers heretofore produced, all as willbe clear from my copending application Sr. No. 368,993, filed Mar. 26, 1920, Pat. No. 1,501,925, and entitled Bagasse fibers and process of producing the same.

Said application discloses the use of a small quantity of caustic soda' having a weight equal to .say 2% of the bone dry weight of the bagasse, the making of a solution of the same in water and heating the bagasse fibers in this solution from say 1 to 3 hours at atmospheric pressure or at a temperature of say from 150 F. to 212 F By proceeding with this comparatively weak solution of alkalivwithout mechanically removing the ith as heretofore, and for this comparativey short time of boiling, the process of said application secures a weight of pith and fibers from the bagasse equal to from 65% to 80% of the bone dry weight w etc., whether they are weak or not, and I may even use strong caustic alkali solutions, provided in all cases I only employ the solution in question, for a time only sufficient to loosen up the encrusting casing with which the bagasse fibers are enclosed, and for a time insufficient to dissolve out any substantial portion of the pith which is a time entirely insuflicient for paper making urposes. The essential feature is that the fibers shall be insufficiently cooked for paper making purposes, and sufliciently cooked to enable the encrusting material to be readily removed later in the beating engine, and puriTng apparatus, without losing the valua le pith material.

Therefore, I find that strong caustic alkali or other equivalent acting solutions may be employed in the cooking apparatus for suchga time as will produce the above mentioned results. When weaker solutions of alkalis, sulphites, sulphates, etc., are employed the same results are attained by watching the action'of the chemicals on the fibers, and by testing the latter from time to time. Usually from 1 to 3 hours will be long enough to cook bagasse fibers for wall board making "purposes, at atmospheric pressure, and by following the present process, I may recover the unspent chemical and use it over again in the next cooking operation.

Not only does the employment of both strong and weak solutions of various chemicals in. the manner stated produce the results set forth, but in addition I find the fibers original strength, like those mentioned in my said copending application, is not impaired in the least which is in marked contrast to the efiects produced by the prior processes, which used on bagasse fibers, ual by weight to from 25% to 40% of the bers and then drastically cooked the latter so that the original strength Was materially lessened.

It will now be clear that in operating under the process of this invention, the

cooking process whether itwbe carried out with an alkali or with any other solution is stopped after the encrusting material holding the individual bundles of bagasse fibers has been loosened up, and-that I may even use strong solutions and stop them as soon as the Elllh begins to dissolve or as soon as the bersbegin to loosen up, or I may use weak solutions and cook the fibers until the said solutions are exhausted; as in my said copending application.

I may also control the strength and resiliency of the fibers by the strength of the solution employed and by the time of cookingas in said copending application.

Further, the alkali, and the other cooking chemicals form compounds with the said en crusting materials or with the binding material between the bundles of fibers which are water soluble, and these said compounds may be 'redeposited on the fibers either by concentrating the liquor or by chemically precipitating them as by adding aluminum sulphate thereto. As the bundles of bagasse fibers obtained as a result of this partial cooking are found to be very soft, pliable, and resilient, with their original strength unimpaired,'as above stated, and as their original pith'is found sticking to them in the form of small knots or protuberances, as also stated above, it is found that the latter serve as valuable felting or entangling agents between the fibers and bundles of fibers in the making of wall boards. 'Ihese said bundles of bagasse fibers thus produced, as in my copending application, are first passed through a beating or other engine to separate the fibers and to break up the individual fibers to a greater or less extent whereupon the finished fiber bundle will be found to have not only its original pith stickingithereto, as above stated, but they also have numerous hook like projections or protuberances all as illustrated in my said copending application #368,993, Patent No. 1,501,925. Therefore, it is found when fibers of this process are worked into wall boards owing to their pith like and hook like protuberances, as well as to their very great strength and resiliency, wall boards made therefrom, like those disclosed in my said copending application, have a tensile strength of more than 10 times that of other boards made from similar fibers according to the prior processes. In other words, when these fibers are formed by water deposition in the manner above disclosed they result in a board or sheet which is a substitute for lumber for a large number of purposes.

As a specific example of this process one may use open containers in the cooking op eration so the temperature need not exceed 212 F. and the pressure need not exceed that of the atmosphere. The usual time required will be found not to exceed one and a half hours upon testing the fibers and the time-of beating the fibers will be found not ,to exceed forty-five minutes in the average case. The loss of original fiber does not usually exceed 15%. Paper making fibers cannot'be produced from bagasse and follow this process.

It is obvious that those skilled in the art may vary the details of the process without departing from the spirit of the invention, and therefore, I do not wish to be limited to the above disclosure except as may I the presence of a'suitable'chemical and at a temperature and for a time suflicient to loosen the encrusting material of said fibers, but insufficient to produce fibers-suitable for paper making; recovering the fibers thus for lumber from flexible 'and strong bagasse fibers which consists in preparing a so'lution of a suitable chemical; cooking said fibers in said solution at a temperature and for a time suificient to loosen their encrusting material, but insuflicient for paper making purposes and to dissolve a substantial portion of the pith present; recovering the fibers thus produced; and forming said fibers by water deposition into a substitute for lumber.

3. The process of producing a substitute for lumber from flexible and strong bagasse and analogous fibers which consists in preparing a solution of a suitable chemical; cooking said fibers in said solution at a temperature not exceeding the boiling point of water and until the encrusting material of the same is loosened; stopping said cooking operation before the said fibers are cooked sufficiently for paper making purposes; passing said fibers through a suitable apparatus to remove thatportion of the encrusting ma-. terlal remaining thereon; recovering the;

fibers thus produced; and forming said fibers by water deposition into a substitute for lumber.

tial portion of their natural pith; subjecting said fibers to the action of suitable mechanism and separating out the encrusting material while leaving the pith adhering to said fibers; recovering the fibers thus pro duced; and forming said fibers by water deposition into a substitute for lumber.

5-. The process of producing a substitute for lumber from flexible and strong bagasse and analogous fibers which consists in cooking said fibers with their natural pith in an alkali solution under atmospheric pressure for a time sufficient to loosen their encrusting materials but insufiic'ient for paper making purposes and to dissolve .a substantial portion of said pith; suitably recovering said fibers; depositing thereon a compound dissolvedfrom said fibers during the cooking operation;'and forming said fibers by Water deposition into a substitute for lumber. 1

6.'The process of producing a substitute for lumber from flexible and strong bagasse and analogous pith carrying fibers which consists in cooking said fibers with their natural pith under atmospheric pressure and at a temperature not exceeding 212 F. 1n

an alkali solution for a time suflicient to rating out said fibers from their encrusting material; recovering the compounds dissolved by the cooking action; andforming said fibers by water deposition into a substitute for lumber.

v 7. The process of producing a substitute for lumber from flexible and strong bagasse pith carrying fibers which consists in cooking said fibers with their natural pith under atmospheric pressure for a time insuflicient to produce paper making fibers and. at a temperature not exceeding 212 F. for a period not exceeding 1 hours in an alkali solution to loosen their encrusting material; separating out said fibers from their encrusting material-by subjecting the same to abeating action; recovering the compounds dissolved by the cooking action; recovering the flexible and strong fibers resulting from said beating action; and forming said fibers by water deposition into a substitute for lumber.

In testimony whereof I afiix my signature.

. .JoHN K. SHAW. 

